Solution : https://service.sap.com/sap/support/notes/454887 (SAP Service marketplace login required)
Key words : 
additional key words integration model rapokzfx cfm2 cfm3 apo relevancy, function module material_apokz_update called t_locked_apokz, relevant material & plant combinations, saved material & plant combinations, material & plant combinations found, additional input parameters, material & plant combinations, apo-relevancy, apo relevancy, reference structure pre01
Related Notes : 
       
| 515499 | Release restrictions for R/3 Plug-In 2002.1 | 
| 440764 | Write field APOKZ not set to application log |